ATOMIC SPECTRUM

                      

The light which atoms give off is made up of specific wavelengths, called lines; observed by a spectroscope, the lines are, collectively, atomic spectra.

In an atom, electrons have specific and discrete energies. There are many more energy states (or levels) in each atom than there are electrons. When an electron transitions (‘jumps’) from one energy level to another, it emits (if going from a higher level to a lower one) or absorbs (vice versa) light – a photon – with a discrete, specific wavelength. In any given set of conditions (pressure, temperature, magnetic field strength, etc), the collection of all those specific wavelengths is the spectrum of the atom … so atomic spectra are the spectra of atoms!

A hot gas

• emits photons with the characteristic wavelengths corresponding to the transitions between different energy levels of the atoms or molecules in the gas.
• This leads to bright lines in the spectrum.